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A Gallium nitride (GaN) field effect transistor (FET) can provide superior performance over a Si-MOSFET due to its low on-state resistance and low junction capacitances. However, a GaN-based converter exhibits higher dead-time loss during reverse conduction. Thus, to improve the efficiency, dead-time optimization is required. This paper proposes simple models for dead-time optimization in a GaN-based buck converter under different load conditions. The proposed models are analytical in nature compared to the conventional models available for Si-based converters. A buck converter prototype is designed using a 100 V GaN device (GS61008P from GaN Systems) and the proposed analytical model-based dead-time optimization techniques are validated experimentally. The proposed modeling techniques can be extended for other GaN-based DC-DC converters.

This study presents a new dead-time measurement method using the gamma attenuation law and generalized dead-time models for nuclear gamma-ray detectors. The dead-time of the Nal(TI) detection system was obtained to validate the new dead-time determination method using very thin lead and polyethylene absorbers. Non-paralyzing dead-time was found to be 8.39 mu s, and paralyzing dead-time was found to be 8.35 mu s using lead absorber for Nal(TI) scintillator detection system. These dead-time values are consistent with the previously reported dead-time values for scintillator detection systems. The gamma build-up factor's contribution to the dead-time was neglected because a very thin material was used. (C) 2021 Korean Nuclear Society, Published by Elsevier Korea LLC.

In this paper, we present the first CMOS SPAD with performance comparable or better than that of the best custom SPADs, to date. The SPAD-based design, fully integrated in 180 nm CMOS technology, achieves a peak PDP of 55% at 480nm with a very broad spectrum spanning from NUV to NIF and a normalized DCR of 0.2cps/m2, both at 6V of excess bias. Thanks to a dedicated CMOS pixel circuit front-end, an afterpulsing probability of about 0.1% at a dead time of3ns were achieved. We designed three SPADs with a diameter of 25, 50, and 100m to study the impact of size on the timing jitter and to create a scaling law for SPADs. For these SPADs, a SPTR of 12.1ps, 16ps, and 27ps was achieved at 6V of excess bias, respectively. The SPADs operate in a wide range of temperatures, from -65C to 40C, reaching a normalized DCR of 1.6 mcps/m2 at 6V of excess bias. The proposed SPADs are ideal for a wide range of applications, including LiDAR, super-resolution microscopy, QRNGs, QKD, fluorescence lifetime imaging, time-resolved Raman spectroscopy, to name a few.

This paper emphasizes on the correction of a misconception among the students about the presence of negative dead time values determined by using a two-source method. To specify the importance of t...

PURPOSE To overcome limitations in the duration of RF excitation in zero-TE (ZTE) MRI by exploiting intrinsic encoding properties of RF pulses to retrieve data missed during the dead time caused by the pulse. METHODS An enhanced ZTE signal model was developed using multiple RF pulses, which enables accessing information hidden in the pulse-induced dead time via encoding intrinsically applied by the RF pulses. Such ZTE with pulse encoding was implemented by acquisition of two ZTE data sets using excitation with similar frequency-swept pulses differing only by a small off-resonance in their center frequency. In this way, the minimum scan time is doubled but each acquisition contributes equally to the SNR, as with ordinary averaging. The method was demonstrated on long-T2 and short-T2 phantoms as well as in in vivo experiments. RESULTS ZTE with pulse encoding provided good image quality at unprecedented dead-time gaps, demonstrated here up to 6 Nyquist dwells. In head imaging, the ability to use longer excitation pulses led to approximately 2-fold improvements in SNR efficiency as compared with conventional ZTE and allowed the creation of T1 contrast. CONCLUSION Exploiting intrinsic encoding properties of RF pulses in a new signal model enables algebraic reconstruction of ZTE data sets with large dead-time gaps. This permits larger flip angles, which can be used to achieve enhanced T1 contrast and significant improvements in SNR efficiency in case the Ernst angle can be better approached, thus broadening the range of application of ZTE MRI.

In low output voltage and high output current LLC resonant converter applications, a synchronous rectification (SR) is essential component for high efficiency and high power density. However, stray inductances in MOSFET package and printed circuit board (PCB) pattern make premature turn- off of SR gate and large SR dead time. To compensate the stray inductance effect and increase system efficiency, a hysteresis band dead time regulation control method is proposed. In the proposed control method, SR dead time is regulated to predetermined dead time target regardless of the stray inductances by using a mixed signal, which includes instantaneous drain voltage information and previous cycle dead time information. As a result, the proposed control method can provide lower conduction losses by the dead time regulation and better transient characteristic by the instantaneous drain voltage information. To verify the validity of the proposed control method, 234-W prototype is built and experimented with the proposed controller, which is implemented with 0.25- μ m BCDMOS technology.

In this work, we report the portable NMR system which provides solutions to the existing problems in miniature CMOS NMR systems. First, a higher IF of 50 kHz is achieved by exploiting separate frequencies for sample excitation and LO, thereby having higher immunity to 1/f noise. The proposed phase detector circuit aligns the experiment trigger with the constant phase difference between two frequencies. It maintains the constant RX output phase in every experiment, allowing the direct signal averaging without extra phase correction. In addition, 40X faster RX recovery with RX BW switching enables the signal acquisition with the dead time of 10 $\mu \text{s}$ . Fast settling improves the acquisition sensitivity. Lastly, a frequency calibration method based on signal peak detection is proposed. Combining the techniques with the fully integrated NMR transceivers, the system demonstrates the NMR experiments to measure the decaying time constant of less than 100 $\mu \text{s}$ . Furthermore, NMR diffusion experiments are performed with the echo spacing of $0.2\sim 8$ ms.

This article proposes a three-stage dead-time adjustment scheme for the leading-leg and lagging-leg switches of phase-shift full-bridge converter (PSFBC) according to the load conditions to enhance the conversion efficiencies at light loads. This article also investigates an iterative rigorous loss calculation for light loads under dead-time adjustment. The proposed iterative calculation can be used to modify the duty ratio of the transition region and estimate the operating currents more accurately; therefore, the losses of a PSFBC at light loads and under the dead-time adjustments can be effectively estimated. A PSFBC prototype with an input voltage of 380 V, an output voltage of 48 V, and a rated output power of 480 W is designed and implemented in this article. Experimental results show that comparing with the PSFBC without the dead-time adjustment and with the conventional dead-time adjustment, the conversion efficiency enhancements of 12.13% and 5.97% can be achieved by the proposed three-stage dead-time adjustment scheme at about 5% load condition, respectively. For a small-scale data center with 100 designed PSFBCs, simulated results indicate that about 3.21 MWh of electricity and 1.03 tons of carbon dioxide emission can be saved and reduced per year, respectively, by the proposed dead-time adjustment scheme.

The adoption of fast-switching silicon carbide (SiC) devices enables power converters to operate at high switching frequencies (e.g., 100 kHz). However, as a limiting factor at high switching frequencies, the dead-time in the conventional pulsewidth modulation (PWM) can cause significant voltage losses, bring serious low-frequency voltage/current harmonics, and reduce the linear modulation region with lower dc-link voltage utilization. Using the dead-time compensation can effectively eliminate the dead-time effect but further reduce the linear modulation region. The dead-time elimination PWM essentially has no dead-time effect. But due to the abandon of drive pulses for generating synchronous rectification, it has a lower converter efficiency, as well as current jumps at zero-crossings. In this article, to overcome the drawbacks of the conventional PWM and the dead-time elimination PWM, a double-modulation-wave PWM for dead-time-effect elimination and synchronous rectification is therefore proposed, where extra drive pulses for generating synchronous rectification are added based on the dead-time elimination PWM. The added drive pulses can also help with mitigating current jumps at zero-crossings. At last, the proposed PWM is experimentally validated and compared with the conventional PWM and the dead-time elimination PWM at 100 kHz on a three-phase converter with SiC mosfet s and SiC Schottky diodes, showing the merits of low voltage losses, low output harmonics, high dc-link voltage utilization, large linear modulation region, and high efficiency.

The active clamp flyback (ACF) converter utilising gallium nitride (GaN) devices with high-switching frequency and high efficiency is impressive in system miniaturisation for AC–DC adapters. Owing to poor reverse conduction of GaN devices, the improper dead time between two switches can cause large power consumption in high frequency. This study proposes a dynamic dead time optimisation technique for GaNs ideal zero-voltage switching (ZVS) to address the issue. It adjusts the clamp switch on time to avoid large reverse conduction voltage stress on the main switch in different loads conditions. In addition, a new control scheme for clamp switch is introduced for enhancing efficiency in light to medium load. These techniques are experimentally verified on a 45 W (20 V/2.25 A) prototype of an ACF converter with a field-programmable gate array. The controller enables the system to operate at 1 MHz and dynamically modulates the dead-time under universal input and full load. With the light load ZVS control scheme, the system can achieve a maximum efficiency of 94.12 and 80.23% in the worst case. The prototyped converter can achieve power density (exclude case and controller) of 18 W/in 3 .

A 10 MHz synchronous boost converter with the subthreshold startup scheme and predictive dead-time control for energy-harvesting systems is presented in this study. The input feed-forward technique is adopted to achieve a fast line response, and a three-stage startup technique is proposed to realise subthreshold voltage startup without using any extra startup circuits or special devices. Moreover, the efficiency of the high-frequency converter can be improved by the proposed predictive dead-time control with a high resolution of ∼300 ps. The proposed converter is implemented in a standard 0.18 μm complimentary metal oxide semiconductor process and occupies a die area of 1.4 × 1.5 mm 2 . Experimental results show that the input voltage ranges from 0.3 to 1.5 V at 1.8 V output, and the minimum startup voltage is 0.3 V. Under V IN = 1.5 V, V OUT = 1.8 V and 150 mA load, the power efficiency can be improved by 2.6% because of the proposed predictive dead-time control. The peak efficiency can reach 90.7% under V IN = 1.5 V. The line transient response can be improved with small overshoot voltage at the output.

BackgroundFor therapeutic applications of several isotopes (e.g.,131I,153Sm,177Lu) in nuclear medicine, the high activities typically applied require accurate dead time correction in early time point imaging. We present a novel, straightforward dead time correction method using the LambertWfunction, which is in principle exact for the paralyzable detector model with a single parameter τ (i.e., dead time).ResultsAs a proof of concept, the method is validated with a simple model: a commonly used isotope,99mTc, with a single photopeak. We measured count rates of a gamma camera both intrinsically and extrinsically (i.e., with collimators) with point sources in air and in a scatter phantom (extrinsic only). τ was estimated for both open window (τOW) and a99mTc photopeak window (τTc), using a “graphical” method for fitting the count rate of decaying sources. These values for τ were subsequently used for dead time correction.τ varied significantly between the different geometries for both energy windows, but τOWwas more reproducible than τTc, particularly for the scatter phantom measurements.τOWmeasured from the phantom measurements was approximately 30% lower than τOWfrom the intrinsic measurement but corresponded within 15% with the extrinsic point source measurements. Accordingly, using the intrinsic τOWled to an overcorrection of 8% at high count rates; τOWfrom the extrinsic point source measurements corrected the phantom measurement to within 2%.However, significant differences were observed between τTcvalues. All measured τTcvalues underestimated dead time losses in a second independent phantom measurement, with even τTcfrom the first phantom measurement underestimating activity with 5–10% at the highest count rates. Based on measurements of the effect of energy window settings and geometry, we tentatively attribute the added dead time losses to pulse pile-up.ConclusionsAnalytic dead time correction based on the LambertWfunction is accurate for the range in which gamma detectors behave as paralyzable systems. However, further investigation indicated measured τ values to be variable with geometry as well as window fraction. We propose that dead time correction should be based on the open window value, τOW, corrected for window fraction.

Background Dead time may affect the accuracy of quantitative SPECT (QPSECT), and thus of dosimetry. The aim of this study was to quantify the effect of dead time on 177Lu-QSPECT and renal dosimetry following peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumours. Methods QSPECT/CT was performed on days 1 and 3 during 564 personalized 177Lu-octreotate cycles in 166 patients. The dead-time data for each scanning time point was compiled. The impact of not correcting QSPECT for the dead time was assessed for the kidney dosimetry. This was also estimated for empiric PRRT by simulating in our cohort a regime of 7.4 GBq/cycle. Results The probability to observe a larger dead time increased with the injected activity. A dead-time loss greater than 5% affected 14.4% and 5.7% of QSPECT scans performed at days 1 and 3, respectively. This resulted in renal absorbed dose estimates that would have been underestimated by more than 5% in 5.7% of cycles if no dead-time correction was applied, with a maximum underestimation of 22.1%. In the simulated empiric regime, this potential dose underestimation would have been limited to 6.2%. Conclusion Dead-time correction improves the accuracy of dosimetry in 177Lu radionuclide therapy and is warranted in personalized PRRT.

High afterpulse probability and the consequent long dead time of free-running InGaAs(P) single-photon detectors have long been the limiting factors to their practical applications. Here we present ...

This study reports a miniaturised discontinuous conduction mode (DCM) variable on-time (VOT) buck converter providing an output of 1.8 V in the input range of 3–12 V to support applications with large wireless coupling. Conventionally, an additional large capacitor has been used as a bootstrap capacitor to drive the high-side switch of buck converters, which prevents minimisation. In this study, a standalone momentary power consumption level shifter is proposed to remove the additional bootstrap capacitor and increase the power conversion efficiency (PCE) in the buck converter. A Zener diode is utilised to reduce the power consumption of the level shifter. In addition, a dead-time-based off-time calibration circuit is proposed to further increase the PCE by reducing the low-side conduction loss. The proposed circuit is fabricated with a TSMC 0.18-µm BCD process, and the core circuit occupies an active area of 0.68 mm2 with two external components. It provides output currents in the range of 20 µA to 3 mA with a maximum switching frequency of 750 kHz. The maximum efficiency of the converter below 5 mW is 80.2%.

The effects of a high background count and a microsecond dead time interval on a gated InGaAs/InP single-photon avalanche photodiode (SPAD) during microsecond luminescence decay registration are discussed. It is shown that the background count rate of the SPAD limits its use for time-resolved and steady-spectral measurements, and that a “pile-up” effect appears in the microsecond range.

With growing decentralized power generation, medium-voltage (MV) dc-dc converters are becoming increasingly important. A three-phase dual-active bridge (DAB3) is a promising topology for high-power...

The wireless process control applications demand high network reliability, low latency, greater energy savings, and secure communication as well as optimal and robust control performance with utmost safety. To address these challenges, the co-design of dynamic proportional-integral-derivative plus (DPIDPlus) controller over WirelessHART network is proposed in this paper for closed-loop control of lag and dead time dominant slower processes. The real-time experiments are conducted using Dust Networks’ SmartMesh WirelessHART sensors testbed to measure the network performance. The wireless control tests are carried out using modified TrueTime 2.0 co-simulator to evaluate the performance of proposed controller. The simulation results show that wireless DPIDPlus controller with dynamic P-gain provides 44.63 % improvement in set-point tracking performance and 5.44 % improvement in disturbance rejection performance as compared to wireless PIDPlus controller for delayed process measurement updates and communication loss intervals.

As the third generation semiconductor with wide band gap, SiC MOSFET not only has fast switching speed and better switching characteristics, but also has certain efficiency in the converter. LLC resonant converter has been widely concerned as an efficient DC-DC converter. SiC MOSFET is used as the primary side switch of half-bridge LLC resonant converter to further improve the efficiency of the converter. Zero voltage switching can reduce the loss and improve the efficiency of half-bridge LLC resonant converter. This paper analyzes the influence of dead time on zero voltage turn-on, and calculates the critical dead time. The switching performance of SiC MOSFET was tested by setting up a dual-pulse experimental platform. By setting up a half-bridge LLC resonant converter, different dead time was set for comparative experiments. The experimental results show that the dead time is too large to achieve zero voltage switching.

Modern photon counting pixel detectors enabled a revolution in applications at synchrotron light sources and beyond in the last decade. One of the limitations of current detectors is reduced counting linearity or even paralysis at high counting rates, due to dead-time which results in photon pile-up. Existing dead-time and pile-up models fail to reproduce the complexity of dead-time effects on photon counting, resulting in empirical calibrations for particular detectors at best, imprecise linearization methods, or no linearization. This problem will increase in the future as many synchrotron light sources plan significant brilliance upgrades and free-electron lasers plan moving to a quasi-continuous operation mode. We present here the first models that use the actual behavior of the analog pre-amplifiers in spectroscopic photon counting pixel detectors with constant current discharge (e.g., Medipix family of detectors) to deduce more accurate analytical models and optimal linearization methods. In particular, for detectors with at least two counters per pixel, we completely eliminate the need of calibration, or previous knowledge of the detector and beam parameters (dead-time, integration time, large sets of synchrotron filling patterns). This is summarized in several models with increasing complexity and accuracy. Finally, we present a general empirical approach applicable to any particular cases where the analytical approach is not sufficiently precise., Comment: 7 figures

Sensorless control technology of PMSMs is of great importance for safety and reliability in electric vehicles. Among all existing methods, only the extended flux-based method has great performance over all speed range. However, the accuracy and reliability of the extended flux rotor position observer are greatly affected by the dead-time effect. In this paper, the extended flux-based observer is adopted to develop a sensorless control system. The influence of dead-time effect on the observer is analyzed and a dead-time correction method is specially designed to guarantee the reliability of the whole control system. A comparison of estimation precision among the extended flux-based method, the electromotive force (EMF)-based method and the high frequency signal injection method is given by simulations. The performance of the proposed sensorless control system is verified by experiments. The experimental results show that the proposed extended flux-based sensorless control system with dead-time correction has satisfactory performance over full speed range in both loaded and non-loaded situations. The estimation error of rotor speed is within 4% in all working conditions. The dead-time correction method improves the reliability of the control system effectively.

In quantum communication systems, the precise estimation of the detector's response to the incoming light is necessary to avoid security breaches. The typical working regime uses a free-running single-photon avalanche diode in combination with attenuated laser pulses at telecom wavelength for encoding information. We demonstrate the validity of an analytical model for this regime which considers the effects of dark counts and dead time on the measured count rate. For the purpose of gaining a better understanding of these effects, the photon detections were separated from the dark counts via a software-induced gating mechanism. The model was verified by experimental data for mean photon numbers covering three orders of magnitude as well as for laser repetition frequencies below and above the inverse dead time. Consequently, our model would be of interest for predicting the detector response not only in the field of quantum communications, but also in any other quantum physics experiment where high detection rates are needed.

Due to its advantages of high sensitivity and low power consumption, Single-photon Avalanche Diode (SPAD) plays an important role in visible light communication. The Multi-pixel Photon Counter (MPPC) based on an array of SPADs has a larger dynamic detection range and has reduced the effect of dead time. However, the existence of dead time leads to a nonlinear response relationship between the pulse of MPPC and the incident photon. In this paper, the maximum likelihood detection algorithm of MPPC under the dead time limit is derived and the corresponding bit error rate simulation diagram is given. Finally, the experiment verifies that the dead time effect makes the output pulse of MPPC not the standard Poisson distribution, while the maximum likelihood detection algorithm based on nonlinear response relation of MPPC synthesized the effect of dead time, which makes the bit error rate performance better.

In this study, a dead-time control circuit is proposed to generate independent delays for the high and low sides of half-bridge converter switches. In addition to greatly decreasing the losses of power converters, the proposed method mitigates the shoot-through current through the application of superimposed power switches. The circuit presented here comprises a switched capacitor architecture and is implemented in AMS 0.35 μm technology. In the implementation, the proposed dead-time control circuit occupies a silicon area of 70 μm x 180 μm. To realize the technique, a two-sided wide swing current source is employed. Each sides of the current source comes with two capacitors, two Schmitt triggers, and three transmission gates. Results show that the low and high sides of the projected half-bridge converter switches respectively require delays of 35 and 62 ns. The performance of the proposed dead-time circuit is evaluated by assembling it with the half-bridge converter. The proposed dead-time prototype achieves a 40% drop in power losses in the half-bridge circuit.

The aim of this work was to improve the SNR efficiency of zero echo time (ZTE) MRI pulse sequences for faster imaging of short-T2 components at large dead-time gaps. ZTE MRI with hybrid filling (HYFI) is a strategy for retrieving inner k-space data missed during the dead-time gaps arising from radio-frequency excitation and switching in ZTE imaging. It performs hybrid filling of the inner k-space with a small single-point-imaging core surrounded by a stack of shells acquired on radial readouts in an onion-like fashion. The exposition of this concept is followed by translation into guidelines for parameter choice and implementation details. The imaging properties and performance of HYFI are studied in simulations as well as phantom, in vitro and in vivo imaging, with an emphasis on comparison with the pointwise encoding time reduction with radial acquisition (PETRA) technique. Simulations predict higher SNR efficiency for HYFI compared with PETRA at preserved image quality, with the advantage increasing with the size of the k-space gap. These results are confirmed by imaging experiments with gap sizes of 25 to 50 Nyquist dwells, in which scan times for similar image quality could be reduced by 25% to 60%. The HYFI technique provides both high SNR efficiency and image quality, thus outperforming previously known ZTE-based pulse sequences, in particular for large k-space gaps. Promising applications include direct imaging of ultrashort-T2 components, such as the myelin bilayer or collagen, T2 mapping of ultrafast relaxing signals, and ZTE imaging with reduced chemical shift artifacts., NMR in Biomedicine, 34 (6), ISSN:0952-3480, ISSN:1099-1492

The transformerless photovoltaic (PV) inverters are preferred in the PV systems because of its higher efficiency and lower cost. Due to the lack of galvanic isolation between the grid and PV panel, the leakage current flows through the parasitic capacitance of PV panel and the grounded neutral point of the power transformer. Since the high-frequency components on the common-mode (CM) voltage is the main source for this current, the switching logic of devices in the PV inverter is usually arranged to suppress the leakage current circulation below the limit of safety standards. The dead-time is also a parameter of CM voltage waveform. The smaller dead-time of the wide-bandgap device GaN HEMT is considered as the advantage on the leakage current mitigation. It is experimentally investigated on the single-phase active clamped snubber-based inverter (ACSBI) topology here. The results with IGBT and GaN HEMT devices used in the ACSBI are compared in this paper.

Electrical vehicles (EV) may breaks down on the road when they don’t have enough energy driving to nearby charging pots. In this paper, an isolated DC/DC converter using dual-active-bridge (DAB) topology is designed for a car to be a portable battery, which can drive where the EV needs and charge it in emergency. Firstly, the actual switching status using optimized Triple-phase-shift (TPS) control is analyzed considering dead-time. The improved TPS control which can realize all- ZVS (Zero Voltage Switch) operation is presented. Finally, a 10- kW prototype is built to verify the enhancement in efficiency.

An on-line compensation for the dead time strategy without the knowledge of the current direction is proposed for PMSM drive based on a current observer. The modifications of the motor reference voltages are achieved by an uncomplicated current observer working in conjunction with the feedforward dead time voltage estimator. Therefore, the distortions on phase currents and torque due to dead time are greatly reduced. The proposed method does not require look-up table and coordinate transformations. It also does not need phase current polarity information or calculation of dead time period. Since the proposed scheme requires no extra hardware and time consuming signal processing algorithms, it is appropriate to use in real-time implementation of AC drives. The proposed scheme has been validated in simulation and implemented using TMS320F28335 DSP. Simulation and practical results validate the effectiveness and the feasibility of the proposed scheme.

A compact and high-efficiency power converter is the main business of today’s power industry for server power applications. To achieve high efficiency with a low-output ripple, an interleaved phase-shift full-bridge (PSFB) converter is designed, built, and tested for server power applications in this study. In this paper, dynamic dead time control is proposed to reduce the switching loss in the light load condition. The proposed technique reduces the turn-off switching loss and allows a wide range of zero-voltage switching. Moreover, the current ripple of the output inductor can be reduced with the interleaved operation. To verify the theoretical analysis, the proposed PSFB converter is simulated, and a 3 kW prototype is constructed. The experimental results confirm that the conversion efficiency is as high as 97.2% at the rated power of 3 kW and 92.95% at the light load of 300 W. The experimental transient waveforms demonstrated that the voltage spike or drop is less than 2 V in the fast-fluctuating load conditions from 0% load to 60% load and 40% load to 100% load.

This paper proposes a method to compensate for the nonlinearity of an inverter, which generally exists regardless of PWM schemes. The nonlinearity originates from the on-state voltage drop of the semiconductor switches and the dead time effect. The effect of the dead time to the control of the inverter has a strong dependency on PWM scheme because the dead time effects occur only at the switching instant of the inverter and the switching is solely decided by PWM scheme. Thus, for the accurate compensation of the nonlinearity, the effect of the dead time should be analyzed with different PWM schemes. The proposed method considers the difference of dead time effect according to different PWM schemes, namely Continuous PWM and Discontinuous PWM. In addition, to implement the proposed method, a new nonlinearity effect identification is introduced, which can separate the on-state voltage drop from the dead-time effect. Several experimental tests are carried out to verify the validity of the proposed method.

GaN devices operating at reverse conduction region causing excessive conduction loss. Therefore, the GaN based switching converters are required to minimize the dead-time. This paper proposes a novel highly digitally adaptive dead-time control for GaN driver. A driver integrated circuit (IC) is designed in 0.18μm BCD GEN2 process to verify the concept. The measurement result achieves 0.7ns dead-time at 2A and efficiency can improve 2.1% at 2A full load compared to 10ns fixed dead-time counterpart.

Dead-time in IGBT-based DC-DC power converters is a well-known issue that causes a limitation of the output voltage and the distortion of the output voltage and current. These distortions are more critical when the converter switching frequency increases and in applications requiring high di/dt. This is especially true for power converters used to supply pulsed electro-magnets in particle accelerators where output waveforms with high slew rates are needed. Several solutions exist to compensate the distortions caused by dead-time; however, in fast and precise applications, the compensation method should be analysed in conjunction with design choices, such as the selection of switching frequency, output filter's inductances and topology. At CERN, hybrid capacitor discharge/switch mode power converters have been developed to supply electro-magnets used for PS beam injection. For standardisation and cost reduction. Because of this design option, dead-time represents 16 % of the switching period thus widely affecting the converter performances. This paper illustrates the effects of dead-time on various design aspects of these hybrid power converters able to produce precise 1ms long current pulses with maximal output current up to 2,5 kA. The converter control loops that have been designed using Energetic Macroscopic Representation approach can partly compensate for the dead-times effects. However, a dead-time compensation technique based on the inductor current sign measurement is nevertheless required to improve the converter performances. It is experimentally demonstrated that this classical compensation method is effective, even in interleaved switching module.

In this paper, an adaptive intelligent controller based on the fuzzy algorithm called LAMDA (Learning Algorithm for Multivariable Data Analysis) is presented in order to identify and regulate a process with variable dead time. The original algorithm has been used for supervised and unsupervised learning, whose main field of application is the identification of functional states of the systems. In this work a modification of LAMDA has been implemented which is capable of online learning using hybrid techniques. The proposal consists of two stages: training stage to learn about the unknown plant in order to establish initial parameters to the controller, and a second phase, called application, in which the control strategy is updated using online learning. The proposed method is tested in the control objective of regulation of a process with variable dead time, to analyze the viability of its utilization in these types of systems in which their dynamics are variable and unknown.

This work introduces a novel gate driver for use with wide-bandgap devices in high-power, high-precision applications. As power amplifiers move to higher operating frequencies, the dead time becomes a significant portion of the overall switching period, resulting in reduced control precision and increased output distortion. The developed driver allows to minimize the dead time inserted between the switching actions of a half-bridge. A prototype using 650 V gallium nitride transistors is developed to evaluate the concept. A low-cost digital isolator connects the high and low-side drivers and prevents cross conduction. As long as one switch is conducting, the other is prevented from turning on. This automatically ensures a minimal dead time determined by the isolators propagation delay. Each driver is powered by an isolated unipolar supply and a differential drive scheme provides negative gate-source voltages to safely turn off the transistors despite high switching speeds. The prototype is tested in a double pulse setup at 400 V and reaches dead times as low as 14 ns.

The receiver dead time is determined by the photon detector’s dead time and the response time interval of its related processing circuit in photon counting lidar. In this paper, the influence of dead time of single pixel and multi-pixel detector on the aperture of receiving lens, ranging error and ranging accuracy is analyzed in detail. From the simulation results, different sizes of receiving lens aperture were selected for detectors with different dead time effects to match the final measurement accuracy. The multi-detector array and multi-channel signal preprocessing circuit can be used to realize independent preprocessing of each detection channel to obtain time mark data of each photon event, and then all data can be processed uniformly based on histogram statistics. With the above two methods, the noise counts of each detected pixel can be significantly reduced, and the dead time effect of each channel can be suppressed. Most importantly, he time-domain drift and ranging error of echo photons can be effectively reduced. Compared with the single pixel, the multi-pixel detector can greatly increase the maximum allowable receiving area, reduce the demand for single pulse energy of the transmitter, and facilitate the engineering implementation.

The dead time setting of Insulated Gate Bipolar Transistor (IGBT) is usually determined by the calculation formula in Infenion technical documents. The parameters in the calculation formula are often obtained according to manual or empirical values, without considering actual application conditions, which inevitably leads to unreasonable setting. In this paper, several main factors affecting the dead time setting are analyzed. Based on the working principle of semiconductor devices, the influence laws of bus voltage, current and temperature on IGBT dead time setting are analyzed, and then the design experiment is carried out to verify.

Background Personalization of 177Lu-based radionuclide therapy requires implementation of dosimetry methods that are both accurate and practical enough for routine clinical use. Quantitative single-photon emission computed tomography/computed tomography (QSPECT/CT) is the preferred scanning modality to achieve this and necessitates characterizing the response of the camera, and calibrating it, over the full range of therapeutic activities and system capacity. Various methods to determine the camera calibration factor (CF) and the deadtime constant (τ) were investigated, with the aim to design a simple and robust protocol for quantitative 177Lu imaging. Methods The SPECT/CT camera was equipped with a medium energy collimator. Multiple phantoms were used to reproduce various attenuation conditions: rod sources in air or water-equivalent media, as well as a Jaszczak phantom with inserts. Planar and tomographic images of a wide range of activities were acquired, with multiple energy windows for scatter correction (double or triple energy window technique) as well as count rate monitoring over a large spectrum of energy. Dead time was modelled using the paralysable model. CF and τ were deduced by curve fitting either separately in two steps (CF determined first using a subset of low-activity acquisitions, then τ determined using the full range of activity) or at once (both CF and τ determined using the full range of activity). Total or segmented activity in the SPECT field of view was computed. Finally, these methods were compared in terms of accuracy to recover the known activity, in particular when planar-derived parameters were applied to the SPECT data. Results The SPECT camera was shown to operate as expected on a finite count rate range (up to ~ 350 kcps over the entire energy spectrum). CF and τ from planar (sources in air) and SPECT segmented Jaszczak data yielded a very good agreement (CF < 1% and τ < 3%). Determining CF and τ from a single curve fit made dead-time-corrected images less prone to overestimating recovered activity. Using triple-energy window scatter correction while acquiring one or more additional energy window(s) to enable wide-spectrum count rate monitoring (i.e. ranging 55–250 or 18–680 keV) yielded the most consistent results across the various geometries. The final, planar-derived calibration parameters for our system were a CF of 9.36 ± 0.01 cps/MBq and a τ of 0.550 ± 0.003 μs. Using the latter, the activity in a Jaszczak phantom could be quantified by QSPECT with an accuracy of 0.02 ± 1.10%. Conclusions Serial planar acquisitions of sources in air using an activity range covering the full operational capacity of the SPECT/CT system, with multiple energy windows for wide-spectrum count rate monitoring, and followed by simultaneous determination of CF and τ using a single equation derived from the paralysable model, constitutes a practical method to enable accurate dead-time-corrected QSPECT imaging in a post-177Lu radionuclide therapy setting.

In the present manuscript, we have studied the affect of choice of operating voltage on the dead time of GM counter, which is a radio-active radiation detector. Choice of operating voltage impacts the dead time which influences the radiation detection time period and efficiency. Nonetheless, the detection of radiation depends on the detector efficiency i.e. collection of electrons created by radiation (which further depends on the dead time interval in case of GM Counter). Lesser dependence of choice of parameters of detector in detector output will provide much authentic information about the radiation. We hereby will try to understand the dead time relation to operating voltage selection. Also, for much understanding we calculated the attenuation coefficient as well its dependence on the selection of operating voltage. Idea is to estimate the extent up to which the operating voltage choice could affect the values of attenuation coefficient.

Quantitative electron probe microanalysis (EPMA) of trace elements using wavelength dispersive spectrometers (WDS) requires high probe current and/or accelerating voltage and long X-ray sampling times to measure weak X-ray signals from target materials. The X-ray count rate of a standard material is extremely high when measured under the same conditions. Consequently, the accuracy of the dead time correction becomes a significant issue for quantification. Accurate dead time correction requires an exact knowledge of the X-ray counting system, including the behavior of the proportional counter and electronic circuits. Each spectrometer has a specific dead time that depends on factors such as electronic circuit design, counter bias, and X-ray energies. The dead time also changes with aging degradation. A pseudo-fixed dead time correction circuit with non-extendable approximation is described that prevents systematic errors in quantitative EPMA caused by inappropriate dead time corrections. The circuit, which is added to the output of the single channel analyzer, includes one extendable and two non-extendable dead time generators with dead times of 0.68 μs, 1.08 μs, and 1.92 μs, respectively. The behavior of the whole system can be treated as non-extendable for most applications, with a dead time of approximately 2.01 μs. The pseudo-fixed dead time circuit suppresses systematic error of the dead time correction to 0.6% or less when the original dead time is between 0.8–2.0 μs and the true X-ray count rate is

In comparison with silicon IGBT, silicon carbide (SiC) MOSFET is expected to reduce the switching loss and the conduction loss and to remove external freewheeling diodes (FWDs). However, its body diode has comparatively high forward voltage; therefore, the diode conduction loss generated during dead time increases. As a result, the loss reduction by the use of the SiC MOSFET can be weakened. This paper proposes a simple dead-time controller integrated in an isolated gate driver in order to reduce the diode conduction loss during the dead time. The proposed method has high speed and high robustness against switching noise by using of a current-sense FET with small parasitic capacitance. As a result, the diode conduction time can be shortened within 0.1 μs. In addition, the proposed dead-time control method can be achieved by existing components, including the current-sense FET, which is currently used for short-circuit current detection in hybrid vehicle applications. The proposed method was applied to a 10 kW boost converter with SiC MOSFET. The experimental results showed 1% higher efficiency of the converter with the proposed dead-time-controlled gate driver compared to that without dead-time control circuit, and the efficiency was the similar level as when a SiC Schottky barrier diode (SBD) was used as FWDs.

In mobile applications, power density highly affects mobility, cost, form factor, and battery time. To improve power density, high switching frequency operation is highly desirable for a power converter. However, with high switching frequency, switching power loss increases significantly, compromising efficiency and battery time. This article presents an on-chip 3-level DC–DC converter, using all NMOS devices as power switches, which reduces switching power loss and silicon cost. To facilitate the all-NMOS power stage operation and enhance the robustness to input supply variation, a 3-switch boost-strap gate driver is designed. Meanwhile, an interception coupling dead-time (ICDT) control is introduced to minimize dead-time related power loss. An integrated circuit prototype was fabricated using a 0.35 μm CMOS process. Robustly working with a variable input voltage from 3 to 6 V, it regulates a programmable power output from 0.4 to 1.6 V, with a maximum power efficiency of 85.5% over a full power range of 800 mW and a maximum power density of 1.07 W/mm2. Thanks to the ICDT control, it achieves a 0.5 ns dead-time over a full-load range of 500 mA.

Within the loose group of studies that are sometimes labelled Heideggerian cinema – studies in which scholars consider film in conjunction with Heidegger's philosophy – little attention has been paid to Heidegger's actual view of cinema. This omission is not only odd (Heidegger's view of film would seem essential for a Heideggerian cinema) but it is also problematic. In the off-hand comments Heidegger directs towards film throughout his collected works he criticises the medium for its covering over of Being, a fact that makes engaging with film through Heidegger's thinking a questionable project. The present article aims to address this omission and to provide a conception of Heideggerian cinema that does not ignore, but answers, Heidegger's criticism. It argues that it is not the technological nature of cinema that is the source of Heidegger's hostility towards the medium but his conception of the film-photographic image as a transparent copy of the world. It is on this basis that cinema is denied the capacity to manifest Being and hence is subject to critique. I then argue that Thompson's notion of cinematic excess reveals that the film-photographic image need not be as transparent as Heidegger assumes and that a cinematic presentation of Being is possible. To explore this idea further the article considers the use of dead time by Michelangelo Antonioni, particularly in his film L'eclisse.

Single photon laser ranging was demonstrated by using small pixel Multi-Pixel Photon Counter (MPPC) and integrated Time Correlated Single Photon Counting (TCSPC) technique and with no gating which is significant for ranging the target with unknown distance. Multi-target distances can be obtained within a few seconds at single photon level signal under daylight background. Thanks to the small pixel MPPC, the dead time was just a few nanoseconds, which is beneficial for reducing the ranging blind zone. The accuracy of the ranging reached sub-millimeter at a several-meter distance.

This paper presents the development of a unified anti-windup strategy for dead-time compensators that copes with stable, integrating, and unstable single-input and single-output linear plants subject to sector-bounded and memoryless input constraints (such as magnitude or rate saturation, the most common cases in practical applications). A discrete-time Filtered Smith Predictor is used as the base control structure and in this specific case it is shown that stability conditions are related to the primary controller and fast model of the plant instead of the whole control structure. As the design is driven directly in the z -domain, implementation of the strategy using a digital controller is immediate. In addition, simulations and a practical experiment using a vapor-compression refrigeration system with time delay are provided and the results show that the strategy has good performance, close to the one presented by optimal model predictive control structures, with the great advantage of requiring no optimization problem to be numerically solved.

To prevent short-circuits between the upper and lower switches of power converters from over-current protection, the dead time is mandatory in the switching gating signal for voltage source converters. However, this results in many negative effects on system operations, such as output voltage and current distortions (e.g., increased level of fifth and seventh harmonics), zero-current-clamping phenomenon, and output fundamental-frequency voltage reduction. Many solutions have been presented to cope with this problem. First, the dead-time effect is analyzed by taking into account factors such as the zero-clamping phenomenon, voltage drops on diodes and transistors, and the parameters of inverter loads, as well as the parasitic nature of semiconductor switches. Second, the state-of-the-art dead-time compensation algorithms are presented in this paper. Third, the advantages and disadvantages of existing algorithms are discussed, together with the future trends of dead-time compensation algorithms. This article provides a complete scenario of dead-time compensation with control strategies for voltage source converters for researchers to identify suitable solutions based on demand and application.

Detector and electronics dead times distort photon detection histograms at high flux, but can be mitigated by probabilistic modeling identifying the sequence of detections as a Markov chain.

Most of the motor driving systems are still using IGBTs as power switches. Switching efficiency – strictly related to switching losses and switching frequency - is of the utmost importance at system level. IGBTs are traditionally driven using a fixed output current, but this solution does not take into account Miller Capacitance (Crss) non-linearity effects. As Crss value spreads of one or even more order of magnitude over the collector-to-emitter voltage (V CE ) swing, the fixed current produces two different dV/dt on the inverter output. This affect switching performances increasing switching losses, due to a slow transient of the IGBT’s gate and VCE, and reducing the possibility of increasing the switching frequency. In order to solve this issue, a two-step gate driver is proposed in this paper, with a focus on experimental results. The proposed solution has been implemented in an integrated circuit developed in a $1 {\mu} \mathrm{m}$ High Voltage (HV) SOI technology. Concept, circuit’s features and bench results are presented, highlighting the advantages of this solution and defining future improvements.

Anti-jerk controller are essential for drive comfort during load-changes, since they reduce undesired driveline oscillations. Hybrid electrified vehicles enable greater degree of freedom to control these oscillations due to the two actuators, namely internal combustion engine and electric machine. At the same time the more complex communication structure of electronic control units in a hybrid electrified vehicle inserts more time delay in the system, which can cause instability in driveline oscillation control. This paper analysis the effect of dead time on a parallel hybrid electrified driveline model with proportional feedback controller and present a feedforward and feedback strategy with dead time compensation. Simulation results of the proposed approach show good step-response behavior and robustness against dead time.